HT4100 4.1, 4.5, 4.9 Discussion, Leaky but good engine in Cadillac Engine Technical Discussion; The 4.9 sure has good power. I cannot believe it is only rated at two hundred horse (cannot remember the ...

Leaky but good engine

The 4.9 sure has good power. I cannot believe it is only rated at two hundred horse (cannot remember the RPM) Has anyone else experienced leaks? 10 years ago (under warrenty) my dad had to get new oil seals and a tranny pan seal done. At least it sounds like is a pretty reliable engine overall, and thanks for all your past input.

I don't know Ralph, My 4.9 155,000 miles no leaks ever! Had the car since new....I had a little oil sweating out around the oil filter line O-rings about a year ago. I replaced the O-rings and that was gone. Thats the only time I've ever seen oil on the outside of this engine......Unless I got sloppy and spilled it!

It seems like all the GM FWD's Ive had run fairly hot. The engine I mean, like when you are cruising slow with your arm out the window, you can just feel the heat from the engine. With my RWD cars I've had, I never noticed this. On the FWD cars including my Pontiac FWD, I've had to change the rubber tranny cooler lines quite often, like every 2 years. My point is that I think for some reason, FWD cars run hotter and/or are harder on the rubber hoses? How often have you had to change hoses, how long should they last?

I doubt the engine runs any hotter, I mean engines are hot but fwd or rwd shouldnt make the engine hotter. Maybe your cars hood was just set up in a different way or maybe the front tires cause more friction that causes heat. Can anyone think of a reason why an engine would run hotter just because of what wheels its sending power to?

As far as FWD engines running hotter than RWD engines, I think the real difference is in the amount of air space around the engine. In a FWD car, both the engine & trans are under the hood & both generate heat (although the trans generates a lot less heat than the engine). Typically, FWD cars have more tightly packed engine bays than RWD cars.

An engine dumps heat to the surrounding air from all surfaces, but the amount of heat dumped depends on the temperature of the air. Cooler air will pick up more heat than air that's almost as hot as the engine. The more open space there is around the engine, the more air will flow and the cooler the air will be. Conversely, the more tightly packed, the more stagnant the air is, and the hotter that air will be. In a tightly packed engine bay, less heat gets dumped to the air around the engine, so the cooling system has to pick up the slack.

True, all of the heat generated by the engine eventually gets dumped to the air, but I think the real difference is in the quantity of air & thus how hot the air gets. Also, in a traditional RWD car, a lot of air flow escapes the engine bay down the trans tunnel & under the floor. The firewall in a modern FWD car is more obstructive to air flow, and I think it results in more air escaping out of the wheel wells.

The FWD cars (specifically Cadillacs) have much higher "under-hood" temps. The engines don't necessarily run any hotter. This is basically due to the facts that Eric presented. This also the reason that Cadillac moved the batteries out of the engine compartment.
And the reason why the fans on your FWD car cars are thermostatic is:
1. Due to the fact that "most" FWD engines are transverse-mounted, the accessory drive is facing to the side of the engine compartment and could not operate a mechanical fan behind the radiator.
2. Space limitations in the ever-shrinking avilabale room in modern engine compartments.
3. Easier "packaging" of the radiator/cooling fan assembly.
4. Less parsitic power loss with electric fans.
5. More accurate contol of engine operating temps which translates into better MPG, lower emmissions, and greater engine component life.

Kat, I thought car batteries are "vented" for gasses? I know my Dad's new DTS has the battery somewhere under a seat, but isn't that a bit dangerous unless it is somehow vented? Are they somehow vented under a seat?

Originally posted by Ralph Kat, I thought car batteries are "vented" for gasses? I know my Dad's new DTS has the battery somewhere under a seat, but isn't that a bit dangerous unless it is somehow vented? Are they somehow vented under a seat?

Not always. A lot of batteries latley don't require ventting as much as they used to, if at all. A lot of the more exspensive ones are totaly sealed and are maintnece free. Basicly they work for XXX amount of time and are then replaced. It's in the design. If it's a dry cell it dosen't give off gas at all so it dosn't require vents and can be stored any where and at any angle.

Originally posted by Scrapyard Not always. A lot of batteries latley don't require ventting as much as they used to, if at all. A lot of the more exspensive ones are totaly sealed and are maintnece free. Basicly they work for XXX amount of time and are then replaced. It's in the design. If it's a dry cell it dosen't give off gas at all so it dosn't require vents and can be stored any where and at any angle.

That's interesting. I test drove a Saturn Ion the other day, and the battery is in the trunk, and it has a little hose connecting to it to vent the gasses. I am curious what system the DTS battery incorporates.